Usage patterns
〈物〉が健全だfor something (finances, an organization, etc.) to be sound
This company's finances are sound.
健全な〈物〉a healthy/sound (mind, body, organization, etc.)
It's important to maintain a sound mind.
健全に〈動詞〉to do something in a healthy or wholesome way
We're careful to make sure the child grows up healthy.
健全性を〈動詞〉to maintain/check the soundness (of a system, finances, etc.)
The government is working to maintain the soundness of its finances.
